import scala.io.StdIn

object Problem012 {

  def proc(n: Int, a: Seq[Int]): Int = {
    val max = 5000000
    if (n == 10) return max - 1

    val checked = Array.fill(max + 1)(false)
    val requiredChar: Set[Int] = a.map(_ + '0').toSet

    var result = -1
    var K = 1
    var usingChar: Set[Int] = Set.empty
    var inRange = false

    def isValid(p: Int): Boolean = (p.toString.map(_.toInt).toSet diff requiredChar).isEmpty
    def outOfRange(p: Int): Boolean = inRange && !isValid(p)

    for {
      p <- 2 to max
      if !checked(p)
    } {
      (p to max by p).foreach(checked(_) = true)

      if (isValid(p)) {
        usingChar ++= p.toString.map(_.toInt).toSet
        inRange = true
      } else if (outOfRange(p)) {
        if (usingChar == requiredChar) {
          val L = p - 1
          result = result max (L - K)
        }
        usingChar = Set.empty
        inRange = false
        K = p + 1
      } else if (!isValid(p)) {
        K = p + 1
      }
    }
    result
  }

  def main(args: Array[String]) {
    val n = StdIn.readInt()
    val a = StdIn.readLine().split(" ").map(_.toInt)

    val result: Int = proc(n, a)
    println(result)
  }
}